The present invention relates to an apparatus for automatically recovering grease from a grease separator. In particular, the present invention relates to a sensor operative for sensing the presence of a thickened layer of grease in the body of effluent.
It is known to pass the effluent from food processing facilities or other operations through devices for removing grease, to enable the grease to be kept out of a sewage system. Some such devices use a sensor for sensing the 10 presence of a thickened layer of grease in the body of effluent in the device. The output of the sensor is then used to control pumping of grease from the device. An example of such a device is the interceptor shown in U.S. Pat. No. 5,705,055, which shows a capacitance level switch located at a specific height in the device. The level switch provides an SPST switch closure to an electric controller to indicate the presence of a certain level of grease and the need to commence pumping of grease.
The present invention is an automatic draw-off grease interceptor for removing grease from an effluent stream containing grease and water. The interceptor comprises a separation tank defining a separation chamber. An effluent inlet is connected with the separation tank for permitting flow of the effluent stream into the separation chamber to form a body of effluent in the separation chamber. The body of effluent has an upper surface. The interceptor includes a pump for pumping grease from the body of effluent in the separation chamber. The interceptor also comprises a sensor operative for sensing the presence of a thickened layer of grease in the body of effluent at a predetermined level. The sensor comprises an insulated conductive probe extending generally vertically in the separation tank from a location above the upper surface of the body of effluent to a location below the predetermined level. The interceptor also comprises means for continuously measuring the capacitance between the probe and the separation tank as the thickness of the layer of grease varies.